TO: Honorable Mayor & Members of the North Port Commission
FROM: Peter D. Lear, CPA, CGMA, City Manager
TITLE: Report on the Proposed Mosaic Desoto County Mine and Potential Impacts on Surface Waters Flowing to the City of North Port.
Recommended Action
Approve recommended actions in Section 9.0 of the Stantec report entitled “Proposed Mosaic Desoto County Mine and Potential Impacts on Surface Waters Flowing to the City of North Port.”
Background Information
A network of waterways connected to the Big Slough/Myakkahatchee Creek in the City of North Port (City) provide stormwater collection/conveyance and recreational functions in addition to serving as a source of raw water for the City’s potable water supply. Proposed significant changes to the watershed upstream of the City, such as the phosphate mine proposed in northwest DeSoto County, could have the potential to adversely impact both water quality and quantity in the Big Slough/Myakkahatchee Creek and other waterways that the City relies upon.
Stantec Consultants Inc. was retained by the City in October 2017, to research and review publicly available literature related to the impacts of phosphate mining on water quality and quantity. Work included review of existing data from the City, the Florida Department of Environmental Protection (FDEP), the U.S Army Corps of Engineers, and review of other literature of mining impacts.
A report of the findings was prepared and includes Stantec’s professional opinion regarding any potential deleterious impacts, and the likelihood of such impacts, to water quality and/or quantity in the Big Slough/Myakkahatchee Creek watersheds. Stantec also provided recommendations for further City actions in Section 9.0 of the report. The following is a summary of these recommendations:
• Collaboratively work with Mosaic and permitting agencies to:
ü Remain fully informed about proposed plan and permit status.
ü Review and comment on proposed plans.
ü Evaluate possibility of using excavated pits as reservoirs to reduce flooding during wet season and release water during dry season.
ü Locate clay settling areas away from Big Slough.
ü Request that extra protections for Big Slough be included in design, as appropriate.
ü Ensure baseline monitoring includes parameters of interest to the City.
ü Request water quantity modeling design for review and provide input.
ü Request that mining occur in the smallest possible footprint at any given time.
ü Request baseline surficial aquifer water level monitoring data collected for the Water Use Permit.
ü Monitor flow data collected for Big Slough at SR72 and at a site within the City.
ü Request baseline water quality monitoring data.
• City to begin monitoring for fluoride at Myakkahatchee Creek at the Appomattox Drive site.
• Review baseline water quality data to determine if additional parameters will be of concern for Big Slough.
Staff has drafted the attached letter for Commission approval to send to key agencies on the City’s concern of the impacts of phosphate mining on water resources.
Strategic Plan
Maintained/Upgraded/Expanded City Infrastructure.
Financial Impact
No financial impact.
Procurement
N/A
Attachments:
1. Report on Impacts of Proposed Mosaic DeSoto Phosphate Mine
2. Proposed Letter to Key Agencies and List of Contacts
3. PowerPoint Presentation
Prepared by: Elizabeth Wong, P.E., Stormwater Manager and Michael Acosta, P.E., Utilities Engineering Manager
Department Director: Juliana B. Bellia, Director, Department of Public Works and Richard J. Newkirk, Director, Department of Utilities